1. Field
The present invention relates to jump rope handles. More particularly, embodiments of the present invention relate to jump rope handles having a plurality of bearings rotationally coupling a handle head with a handle grip.
2. Background Information
Jump ropes are exercise equipment used for play, exercise, training, and sport. Referring to FIG. 1, a pictorial view of a jumper using a jump rope is shown. A typical jump rope includes a rope 100 with a handle 102 at either end for a jumper 104 to grip and control the swinging of the rope. In the sport of speed rope skipping, a jumper may try to complete as many jumps as possible within a particular amount of time. For example, the jumper could complete as many as one hundred jumps during a thirty second interval. To achieve this intensity of jumping, a specialized jump rope, sometimes referred to as a speed rope, may be required.
Referring to FIG. 2, a cross-sectional view of a portion of a jump rope handle is shown. A typical speed rope handle 102 may include a handgrip 202 for a jumper to hold and a nut 204 fixed to rope 100. Nut 204 may rotate relative to handgrip 202 such that the entire rope 100 swings about a handle axis. This differs from conventional jump rope handles in which a portion of rope 100 remains fixed relative to handgrip 202 and a portion of rope 100 swings about the handle axis such that a region of localized cyclic bending stresses occurs in rope 100 between the portions. By rotationally decoupling rope 100 from handgrip 202 as shown in FIG. 2, rope speed and control may be improved to facilitate faster jumping.
In a typical speed rope, nut 204 is fixed to a screw 206 that passes through a retaining element engaged with handgrip 202, e.g., screw 206 may extend through a bushing 212 pressed into an end of handgrip 202. Nut 204 may be threaded onto a threaded portion 208 of screw 206 to retain a screw shank 210 within bushing 212, allowing shank 210 and nut 204 to rotate freely relative to handgrip 202. However, during use, as rope 100 swings quickly around the jumper, transverse loading in a radial direction may be applied to the threaded portion 208 of screw 206 by rope 100, and therefore, the cantilevered screw 206 may transmit both transverse and axial loads, as well as substantial torque, to bushing 212. More particularly, the cantilever load placed on screw 206 by rope 100 may result in loading, and thus, friction between screw 206 and bushing 212. This friction may reduce an achievable jumping speed. Furthermore, axial and torsional loading of bushing 212 can result in material stresses that bushing 212 is not designed to withstand, which may lead to failure of bushing 212. Thus, conventional speed ropes may not be durable and/or may prevent a jumper from reaching their performance goal.